known as the New Territories. The British formally took possession on 16 April 1899. Japanese occupation In 1941, during the Second World War, the British reached an agreement with the Chinese government under Generalissimo Chiang Kai-shek that if Japan attacked Hong Kong, the Chinese National Army would attack the Japanese from the rear to relieve pressure on the British garrison. On 8 December, the Battle of Hong Kong began when Japanese air bombers effectively destroyed British air power in one attack. Two days later, the Japanese breached the Gin Drinkers Line in the New Territories. The British commander, Major-General Christopher Maltby, concluded that the island could not be defended for long unless he withdrew his brigade from the mainland. On 18 December, the Japanese crossed Victoria Harbour. By 25 December, organised defence was reduced into pockets of resistance. Maltby recommended a surrender to Governor Sir Mark Young, who accepted his advice to reduce further losses. A day after the invasion, Chiang ordered three corps under General Yu Hanmou to march towards Hong Kong. The plan was to launch a New Year's Day attack on the Japanese in the Canton region, but before the Chinese infantry could attack, the Japanese had broken Hong Kong's defences. The British casualties were 2,232 killed or missing and 2,300 wounded. The Japanese reported 1,996 killed and 6,000 wounded. The Japanese soldiers committed atrocities, including rape, on many locals. The population fell in half, from 1.6 million in 1941 to 750,000 at war's end because of fleeing refugees; they returned in 1945. The Japanese imprisoned the ruling British colonial elite and sought to win over the local merchant gentry by appointments to advisory councils and neighbourhood watch groups. The policy worked well for Japan and produced extensive collaboration from both the elite and the middle class, with far less terror than in other Chinese cities. Hong Kong was transformed into a Japanese colony, with Japanese businesses replacing the British. However, the Japanese Empire had severe logistical difficulties and by 1943 the food supply for Hong Kong was problematic. The overlords became more brutal and corrupt, and the Chinese gentry became disenchanted. With the surrender of Japan, the transition back to British rule was smooth, for on the mainland the Nationalist and Communist forces were preparing for a civil war and ignored Hong Kong. In the long run the occupation strengthened the pre-war social and economic order